1. Field of the Invention
The present invention relates to fuel shut-off valves used for shutting off flow of fuel.
2. Description of the Related Art
A fuel shut-off valve is known that is provided at an upper portion of a fuel tank, for example, of an automobile. The fuel shut-off valve prevents fuel from flowing out of the fuel tank, for example, when an automobile has been excessively inclined or rolled over. The fuel shut-off valve is also called a “fuel cut-off valve” or a “rollover valve.”
In general, the fuel shut-off valve is closed to prevent fuel flow flowing out of the fuel tank in response to the upward movement of the float as the fuel level within the fuel tank rises. To this end, a known device, such as that disclosed in Japanese Laid-Open Patent Publication No. 2001-82270, has proposed to provide communication holes in a bottom wall of a casing defining a valve chamber that vertically movably receiving the float, so that the communication holes communicate between inside of the fuel tank and the valve chamber. Therefore, the fuel or gas within the fuel tank flows into the valve chamber via the communication hole and the fuel flowing into the valve chamber flows into the fuel tank.
The above structure of the known device is shown in FIGS. 8 and 9 that are a plan view showing the communication hole and a sectional view taken along line IX-IX in FIG. 8, respectively. As shown in FIGS. 8 and 9, each of communication holes 100 of the known device is configured as a circular straight hole extending vertically through a bottom wall 102 and having a fixed diameter d (see FIG. 9).
In the case of the known device, there is a problem that the fuel flowing into the valve chamber cannot be smoothly discharged into the fuel tank due to the straight configuration of the communication holes 100. Therefore, when the automobile turns around, the fuel may flow from the valve chamber to the outside (e.g., a vapor passage communicating with a canister) to cause a phenomenon known as “spillage”.
Therefore, there is a need in the art for a shut-off valve that enable fuel flown into a valve chamber to be easily discharged into a fuel tank.